Thermally responsive means



March 29, 1955 A. J. HATCH THERMALLY RESPONSIVE MEANS Flled April 22, 1950 Fl G.- I

ARTHUR J.

HATCH INVENTOR ATTORNEY United States Patent 2,705,259 THERMALLY RESPONSIVE MEANs Arthur J. Hatch, Toledo, Ohio, Electric Corporation, Toledo, Delaware assignor to The Strong Ohio, a corporation of My invention relates to thermally responsive devices of the type including a thermally responsive element comprising a plurality of laminations having different coefficients of thermal expansion and designed to operate by deflection resulting from unequal expansion or' contraction of the laminations upon change in temperature, and the principal object of my invention is to provide an improved device and an element of the indicated type.

In the drawings accompanying this specification and forming a part of this application I have shown for purposes of illustration what I now consider to be the best method of carrying my invention into practice; for example, for the control of an electric circuit, and in these drawings:

Figure 1 is what may be termed a front elevation of the selected embodiment of my invention;

Figure 2 is then a side elevation, viewed from the right side of Figure 1; and- Figure 3 is a view on the line 3-3 of Figure 1.

The selected embodiment of my invention comprises an'assembly consisting of a base 11 and glass bulb 12,

2,705,269 Patented Mar. 29, 1955 piece stamped element, depends upon preventing such problem by deforming the connecting section 21 to form of a type used for electronic tubes, having the margin of the bulb 12 sealed to the base 11, and in which the base is provided with terminal pins 13 by which .the tube is mounted in a cooperating socket, not shown, and for that reason the base 11 is herein shown as provided with four of the terminal pins 13, although I employ and require only the two pins 13a and 13b.

Further the selected embodiment comprises a one piece bi-metallic element 20 conveniently formed by a single stamping operation and having a surface shape providing a connecting section 21, a support arm 22 extending from one edge of the section ably secured to the inner end of the terminal pin 130 at a distance from the connecting section 21, and a second arm 23 extending from the same edge of the connecting section 21 and carrying a contact 24 in position to engage a stationary contact 25 mounted on the inner end of the other terminal pin 13b.

Under these circumstances, inasmuch as the two arms 22 and 23 extend generally in the same direction from the connecting section 21, change in temperature of the element 20 as a whole will produce only such slight movement of the contact 24 as may result by reason of difference in effective lengths of the arms 22 and 23, but in a situation where a beam of light is directed selectively onto the arm 22 or the arm 23, as in my co-pending application Serial Number 133,577, filed December 17, 1949, now Pat. No. 2,622,224 dated December 16, 1952, this same characteristic operates to render the device substantially independent of ambient temperatures, and thus responsive substantially entirely to the effect of the directed beam.

Thus when the beam impinges on the arm 22, the increase in temperature of the arm 22 will, for example, flex the arm 22 to move the contact 24 away, or further away, from the stationary contact 25, but when the beam impinges on the arm 23, the increase in temperature of the arm 23 will then flex the arm 23 to move the contact 24 into engagement, or into tighter engagement, with the stationary contact 25.

However, for this action it is important that the connecting section 21 shall not warp or twist to any material extent, otherwise the functioning of the device is essentially inaccurate and defective, and thus success of a device of the present type, and particularly of a one- 21 and welded or otherwise suita rib 26 of appropriate depth, extending longitudinally of the extent of the section 21, and entirely effective to prevent material warping or flexing of the section 21 intermediate the arms'22 and 23, and therefore to afford the required degree of accuracy of operation.

As will be understood, this rib may be formed very easily and inexpensively, by a simple stamping operation, and in fact, in the same operation in which the element 11 is formed from the initial blank or strip, and according to present, experience, preferably is located adjacent to or at that edge of the section 21 from which the arms 22 and 23 extend.

As'will also be understood, in any event the bulb 12 protects the enclosed parts against mechanical injury, and preferably is either evacuated or filled with an inert gas, such as nitrogen, thereby to protect the enclosed parts against oxidation, but preferably is filled with the inert gas, thereby also to facilitate dispersion of heat and accelerate response of the device to the selected cause.

In the particular use above described, the bulb 12 preferably is provided with an opaque coating, not shown, leaving only a window for the passage of the beam to which the device is to respond, thus rendering the device further insensitive to other influences.

However, for other uses this coating may be omitted,

also for this or any other use, or generally for all uses, various changes may be made, within the scope of my invention, and therefore the present disclosure is and is to be taken as only for purposes of illustration, and I claim:

1. A thermal responsive switch constructed to operate in response to reception of radiant heat and to be substantially unaffected by changes in ambient temperature within a normal range, comprising a thermal responsive element of the type comprising a plurality of laminations of different coefficients of thermal expansion and designed to operate by deflection resulting from unequal expansion or contraction of said laminations upon change in temperature, said element being of a shape providing two arms of uniplanar form throughout their length and normally free from stress so as to lie in parallel relation in substantially the same plane and a connecting section extending between corresponding ends of said arms and deformed to provide rib means constructed and arranged to stiffen said section against flexing intermediate said arms, support means mounting said element by connection of one of said arms to said support means at a distance from said connecting section, relatively stationary contact means constructed and arranged to be engaged by the other of said arms at substantially the same distance from said connecting section, a glass envelope enclosing said thermal responsive element, and an inert gas sealed in said glass envelope.

2. A thermal responsive device constructed to operate in response to reception of radiant heat and to be substantially unaffected by changes in ambient temperature within a normal range, comprising a base, a coacting member carried by said base, said base and said member together forming a hermetically sealed chamber, said base being substantially opaque, and said member being generally substantially opaque but comprising a window section, a thermal responsive element of the type comprising a plurality of laminations of different coefficients of thermal expansion designed to operate by deflection resulting from unequal expansion or contraction of said laminations upon change in temperature mounted in said chamber, of a shape providing two arms of uniplanar form and normally free from stress and a connecting section extending between corresponding ends of said arms and deformed to provide rib means constructed and arranged to stiffen said section against flexing intermediate said arms, and constructed and arranged to operate in response to radiant heat received through said section upon one of said arms, support means mounting said element by connection of one of said arms to said support means at a distance from said connecting section, and coacting means constructed and arranged to coact with the other of said arms at substantially the same distance from said connecting section.

3. A thermal responsive device including a base; a hermetically sealed chamber secured to the base; an inert gas contained in said chamber, a pair of current conducting members extending through said base; a thermal responsive element formed of laminations ot' diflerent coefficients of thermal expansion, said element being of a-shape providing two spaced arms of uniplanar form throughout their length and normally free from stress so as to lie in parallel relation in substantially the same plane and a connecting portion extending between adjacent ends of said arms, said connecting portion being formed with rib means arranged to resist flexing intermediate said arms; one of said current conducting members being connected to one arm of said element and adapted to support the element within the sealed chamber, the other current conducting member and arm provided with cooperating contact means for completing and interrupting a circuit through the current conducting members dependent upon the relative position of the thermal responsive element, said chamber having a substantially transparent zone for admitting the passage of radiant heat to the thermal, responsive element from a source exteriorly of the chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,461,523 Fransson July 10, 1923 1,851,657 Appelberg Mar. 29, 1932 2,112,328 Bodle Mar. 29, 1938 2,171,861 McCabe Sept. 5, 1939 2,171,895 Sardeson Sept. 5, 1939 2,192,960 Bokovoy Mar. 12, 1940 2,284,383 Elmer May 26, 1942 2,313,745 Hays, Jr., et a1 Mar. 16, 1943 2,379,300 Hodgkins June 26, 1945 2,542,115 Brown Feb. 20, 1951 2,553,197 Lems May 15, 1951 

